Tech Briefs

Innovative eel passage facility transports fish above dam

An innovative eel passage facility installed at the 912-MW St. Lawrence-FDR Power Project on the St. Lawrence River in New York began operation on July 1, 2006. The facility consists of more than 1,100 feet of connected pipes and ramps that safely move American eels upstream of the dam. A unique feature of the facility is a passage pipe, which releases eels about 900 feet upstream of the dam. This minimizes the chances that passed eel will fall back through the turbines.

Eels enter the ladder and climb a series of specialized ramps containing a grid of round pegs. The eels push against the pegs to move up the 35-degree incline through a constant flow of about a quarter inch of water. After climbing more than 100 vertical feet of ramps, the eels enter a 6-inch-diameter passage pipe and swim upstream against a constant flow of about 1 foot per second. Upon exiting the pipe, eels enter a perforated ductile iron pipe 4 feet in diameter that provides a safe haven for their reentry into the river.

The passage pipe was designed for the facility after studies conducted during its development indicated that about half of the eels released immediately upstream of the dam would fall back through the turbines. With the greater distance upstream and the safe haven for reentry, the New York Power Authority (NYPA), the project owner, expects the fallback rate will be less than 5 percent.

The eel ladder installed at the 912-MW St. Lawrence-FDR Power Project features specialized climbing ramps containing a grid of round pegs. The eels push against the pegs to move up the 35-degree incline through a constant flow of about 0.25-inch of water. Click here to enlarge image

To test effectiveness of the structure, NYPA is conducting studies using five radio frequency identification (RFID) readers supplied by Biomark Inc. in Boise, Idaho, to track eels as they move through the facility. In addition, NYPA installed infrared optical counters supplied by Milieu Inc. in Quebec, a biological consulting firm with expertise in eel behavior, to count eels as they exit the ladder and passage pipe.

From July 1 through September 30, 2006, the ladder passed more than 8,100 eels. Operation continued until the end of October. Average passage time was only 1.5 hours. One eel passed the entire facility in 32 minutes!

Working with Milieu Inc., C&S Engineers of Syracuse, N.Y., designed the US$1.9 million structure. B-S Industries of Gouverneur, N.Y., built the structure.

Hydropower Generation Report Click here to enlarge image

– By Kevin McGrath, senior environmental scientist, and Thomas Tatham, senior licensing specialist, both with NYPA. NYPA won an Outstanding Stewardship of America’s Waters Award from the National Hydropower Association for its eel passage facility.

NEMA releases new standard for cable tray installations

The National Electrical Manufacturers Association announces release of a new standard, VE 2-2006, Cable Tray Installation Guidelines. This third edition of the standard is intended to be a practical guide for the proper installation of cable tray systems.

Specifically, this publication addresses shipping, handling, storing, and installing cable tray systems. The standard also provides information on maintenance and system modification.

VE 2-2006 has been revised to reference the 2005 version of the National Electrical Code. It also provides clarification for grounding and bonding cable trays, as well as recent cable tray product developments.

– This standard may be downloaded free from the Internet: stds/ve2.cfm. To purchase a hard copy for US$69, visit the Internet or call (1) 800-854-7179.

New filter placement method used at Saluda Dam

During construction of a new backup dam at the 206-MW Saluda hydro project on the Saluda River in South Carolina, contractor Barnard Construction Company Inc. of Bozeman, Mt., developed a new filter placement method.

The new method allows a dam constructor to eliminate the possibility of contamination of filter material, minimize material rehandling, and reduce the amount of wasted material, says Dan Hertel, vice president of Barnard.

The method is an alternative to other techniques used to place filter zones, such as bedding boxes, belly dumps, or front-end loaders. These methods generate a great deal of waste as a result of unconfined placement of the material, Hertel says.

The new backup earthen dam at Saluda features a double chimney filter zone surrounding the core material of the structure, both upstream and downstream. The upstream system consists of a 4-foot zone of a 3/8-inch or smaller sand fine filter and a 4-foot zone of a 1-inch or smaller coarse filter. The downstream filters are 6-foot zones of the same products.

To place these filters, Barnard modified a Cat 740 ejector truck. This modification involved: adding a central steel divider in the bed of the truck to keep the fine and coarse filter materials separate; installing a steel chute to more precisely direct the placement of the fill material; and modifying the tailgate system to accommodate this chute.

The truck was loaded with filter material directly from the stockpiles. Drivers used the center core material of the dam as a haul road, to limit traffic on the filters. Once in the placement location, the truck straddled the filter zones and ejected the filter materials down the chute. The driver controlled the depth of the filter zones using the truck’s speed and motor revolutions per minute (rpm).

A small bulldozer followed the truck to place the filter to the proper width and thickness. This bulldozer featured a blade that had been modified by adding a central divider to keep the fine and coarse filter material separated while they were spread.

With four trucks using this method, Barnard was able to place about 100 cubic yards of filter material per hour.

This filter placement method provides several benefits over traditional methods, Hertel says. First, it avoids breakdown of the filter material during placement by minimizing rehandling. Second, it eliminates contamination of the filter during placement. Third, it keeps the filter material segregated during handling, thus continuing to minimize contamination.

The system provides another benefit – reduction in waste, Hertel says. By reducing the lift thickness to about 9 inches at Saluda (rather than the 12 inches allowed in the contract), waste was just 10 percent, or 6 inches of overbuild on each filter zone. This saved about 40,000 cubic yards of filter material at Saluda, Hertel says.

This new method could be used for a variety of filter applications, Hertel says.

New technique helps to optimize water use at hydro facilities

Utility Hydro-Québec is using a technique known as “multilag autocorrelation of inflows” to optimize water use at its hydro facilities. This technique takes into account inflow persistence – long periods of low or high inflows in the historical record of daily inflows. Typical reservoir management methods do not account for this long-term variation in inflows and thus may not be reliable for optimizing project operations.

To represent inflow persistence, also known as multilag autocorrelation, researchers with Ecole Polytechnique de Montréal developed a hydrologic variable equal to the conditional mean of the daily inflow. They then devised a new method of inflow management for determining the probability distribution of the variable for one day as a function of the hydrologic variable and the inflow of the preceding day.

Typically, management programs assume that the reservoir inflow on a given day is independent to that of the preceding days. However, in reality the inflow on that day can be correlated to inflows on several preceding days. The new method takes into account this correlation, which can then be used to adjust reservoir operating policy.

The new method is most suited for management of three or fewer interconnected reservoirs.

– For more information on this technique, contact André Turgeon, Ecole Polytechnique de Montréal, (1) 514-340-6053; E-mail: andre.turgeon@

Library houses data on water resources in the Columbia Basin

The StreamNet Library houses information on hydrology, fisheries science, and hydropower in the Columbia River Basin in the Pacific Northwest. Resources available include books, journals, computer files, and technical reports on fisheries, ecosystems, and other relevant subjects.

The library contains about 20,000 items, including “grey” literature such as consultants’ reports, state government documents, and reports from non-profit organizations. Users can access environmental impact statements, Federal Energy Regulatory Commission licensing documents, and water quality reports.

Information in the library is available to both the scientific community and the general public who are interested in issues surrounding the Columbia Basin and salmon recovery efforts. The library offers research assistance, interlibrary lending and borrowing, and document delivery.

This composite photo of a riverine area was produced using low- elevation aerial photography. This technology has been used in several hydro project studies, including assessment of instream flow options and effects of flow fluctuations on habitats. Click here to enlarge image

Data is available both online at www. and by visiting the library at: 729 NE Oregon Street, Suite 190, Portland, OR 97232; (1) 503-736-3581.

StreamNet was established in 1992 using funding from the Bonneville Power Administration’s Fish and Wildlife Program.

Low-elevation aerial photography provides map of riverine areas

Low-elevation aerial photography, commonly referred to as balloon photography, is being used to create photographs and maps of riverine areas for use in hydro project instream flow and habitat enhancement studies and assessments.

Balloon photography offers an alternative to orthorectified aerial photography, which involves taking photographs at high elevation that cover relatively large areas, says Dirk Pedersen, aquatic ecologist with Stillwater Sciences, a company that specializes in scientific approaches and technologies for environmental problem-solving in aquatic and terrestrial ecosystems. Pedersen says he finds low-elevation aerial photography useful for creating spatially accurate, high-resolution photographic images and base maps of relatively small (0.1 to 10 hectares) riverine areas. He has used the images in several hydro project studies, including assessment of instream flow options, effects of habitat enhancements, and effects of flow fluctuations on habitats.

Low-elevation aerial photography involves suspending a digital camera from a helium-filled balloon or blimp flying at an altitude of as low as 10 meters. The balloon is navigated from the ground, either directly or by remote control. Overlapping photos are taken using a wireless remote control.

From these photos, a mosaic image is created in a geographic information system (GIS) framework using control points on the ground. Control points used for georeferencing and image rectification are identified in the field for each photograph based on the photo coverage and extent of overlap with adjacent images. The mosaic photo developed using this method provides an accurate, high-resolution photo base for conducting field mapping and spatial analyses.

Examples of the use of low-elevation aerial photography for various types of studies related to hydroelectric projects include:

– Assessing instream flow options in the upper McKenzie River in Oregon. The study involved mapping suitable fish habitat at various flows based on the habitat preferences (depth, velocity, substrate, and cover) of different fish species and life stages. Habitat was mapped onto a mosaic photo base map and used to extrapolate habitat within specific reaches at different flows. Extrapolated estimates of available habitat were used to model population dynamics of bull trout and chinook salmon under different instream flow scenarios.

– Assessing the effects of habitat enhancements on the carrying capacity of juvenile coho salmon in the North Umpqua River in Oregon. This ongoing work involves evaluating the effectiveness of habitat enhancements using large woody debris and boulders to increase coho salmon carrying capacity and production (see “Tech Briefs,” October 2006).

– Assessing the effects of daily flow fluctuations on suitable fish habitat in the South Fork American River in California. The study involved mapping water depths and velocities at various flows onto a mosaic photo base map to evaluate how habitat suitability for target fish species and life stages changes over a daily flow fluctuation cycle.

Equipment used to perform this work depends on the application and setting. Small channels with a low riparian canopy require compact equipment, including a small, durable balloon and lightweight camera equipment. Larger channels without canopy limitations require more buoyancy, increased stability due to greater wind exposure, and longer remote communication, Pedersen says. Equipment requirements and costs range from $3,500 for a tethered balloon apparatus to more than $25,000 for a self-powered remote-controlled blimp.

Hydro Review always welcomes your suggestions for magazine articles and departments you believe would be helpful to colleagues.

Please send your ideas to the Editor, Hydro Review, 410 Archibald Street, Kansas City, MO 64111-3046; (1) 816-931-1311, extension 106; E-mail:

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